In the field of bringing fluids into contact with solid materials, the invention relates to the use of containers for granular materials and which are permeable to fluids and the general shape of which is substantially a tetra-hedron. The containers have a surface area:volume ratio which is particularly suitable for the use of granular material, particularly for catalysis, adsorption, ion exchange and distillation.
The use of these containers relates particularly to adsorption, distillation, ion exchange, as well as simultaneous distillation and catalysis.
Materials in the form of small, discrete particulate solids are used in many industrial applications: this is the case for instance with ion exchange, adsorption on activated charcoals, molecular sieves or activated silica, or for catalytic reactions or liquids or gases which have to be in contact with these materials.
In a fixed bed, these materials offer considerable resistance to the passage of fluids, resulting in substantial losses of potential, formations of preferred routes and a more or less regular grading by order of particle size. Formations of gas pockets may occur giving rise to piston effects which lead to clogging.
Granular materials in an expanded or fluidized bed are subject to considerable abrasion and fracture, thereby losing their efficacy and giving rise to fines which have a particular tendency to clog, causing major problems.
Finally, for certain applications, there is a need for a large surface contact area for a given volume of granular material or even free space around caked granules.
Therefore, certain operations have been proposed as a way of bringing solid granular materials in contact with liquids or gases by enclosing the said materials in containers or bags which are permeable to the fluids but in which the points of fluid passage (pores or spaces, interstices or meshes, if grids are used or woven or knitted textile materials are involved) are sufficiently small to trap the finest particles of the solid materials.
To-date, the bags or containers proposed have proved to be inadequate in that they either become deformed when they are stacked or they have an insufficient surface area:volume ratio or they may be difficult or expensive to manufacture.